The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure
Universal serial buses (USBs) are used by a wide variety of devices to communicate, one with another. For example, a USB may be used in a traditional desktop environment to connect a desktop computer with input devices (e.g., a keyboard and mouse), output devices (e.g., a printer and speakers), storage devices (e.g., a hard disk drive), and so on. In some instances, however, techniques employed by a traditional USB may be inefficient, such as by causing inefficient power consumption which may hinder implementation outside of a traditional desktop environment.
The overhead encountered using a traditional USB suspend/resume protocol may make USB unsuitable for implementations having limited resources, e.g., mobile devices that use a battery, as well as devices that use frequent suspend/resume operations to conserve resources. For example, operation of a traditional wireless local area network (WLAN) device may be suspended for predetermined periods and resumed in order to conserve power, such as to check for network traffic for a period of three milliseconds every 100 milliseconds (ms). Traditional USB suspend/wakeup techniques, however, may add a significant amount of overhead (e.g., time and power) to a suspend/resume operation of the device during each periodic interval. For example, a traditional USB suspend/resume protocol may have a minimum of 30 ms overhead, which may include a 3 ms quiet period for the device to assure that the USB is being suspended, a minimal 5 ms suspended period before wakeup of a host, and a 20 ms resume signal. Further, host driver processing latency may contribute 10 to 50 ms additional overhead. Thus, the amount of time used to perform a traditional USB suspend/resume protocol as well as the amount of power consumed during this performance may make USB unsuitable for mobile applications.